Flexible manufacturing involves a work machine, such as a six-axis articulating robot, typically placed at each work station. The logistical supports in flexible manufacturing consist of a central controller or computer to manage the work flow and a material handling systems to provide supplies as needed to the different work stations. In these systems the logistical portion can be programmed for different parts and volumes of parts, making the configuration more flexible.
The most powerful form of flexible manufacturing utilizes robots in the material handling portion of the system. This increases the programming capability of the material handling portion of the logistical support system. These can have very complicated forms of programming regarding the routing and scheduling portions of the material handling process. The flexibility of the robots is determined by the sophistication of the arms of the robot. Much research and development has been done with robotic movement, employing similar technologies to those used in multi-axis machinery. This capability can be used to precisely align part placement and coordinate other arm movements.
One limitation of conventional industrial robots is the interface between the robot and the payload the robot is manipulating. Typically, the robot is uniquely configured to suit a particular end-of-arm tool that would provide the most versatility in the particular application. What this means in practice, however, is that the end-of-arm tool must be redesigned for different applications. When production runs are scheduled, they must include steps for frequently changing of the end-of-arm tools to meet the variety of various payloads being used in the production run.
FIG. 1 is an example of a prior art end-of-arm (EOA) tool 10, wherein a spring-loaded level compensator 12 has a distally mounted gripper 14, as for example in the form of a vacuum assisted suction cup 16, but this may be otherwise, such as an electromagnet. The spring-loaded level compensator 12 is in the form of a shaft 18 which is slidable and guidably mounted relative to a housing 20 and biased by a spring 22 such that the nominal position is for the gripper 14 to be remotely positioned with respect to the housing 20. The shaft 18 has a port member 24 at its proximal end which is interfaced with an actuation source for the gripper 14, as for example an air line 26 for a suction cup gripper or an electrical feed for an electromagnetic gripper. A base plate 28 is connected with the housing 20, wherein the base plate provides a suitable connection platform to a robotic arm.
In operation, with the EOA tool 10 at its nominal configuration, a robot to which the ratcheting EOA tool is connected, maneuvers so that the gripper 14 approaches a payload of arbitrary shape. Upon a selectively adequate pressed contact as between the gripper and the payload, wherein as the shaft slides relative to the housing the spring compresses, the gripper is actuated to grip the payload, whereupon the robot moves the payload as determined. Upon conclusion of robotic movement of the payload, the gripper is deactivated, and the spring returns the EOA tool to its nominal configuration.
Another limitation of conventional robots is that spring-loaded end-of-arm tools, which allow for surface irregularity (level) compensation of payloads of differing geometric shapes, utilize spring-loaded level compensators that always apply spring biasing to the shaft, which biasing has the disadvantage of tending to always force the shaft to its nominal position.
Accordingly, what remains needed in the art is an end-of-arm tool spring-load level compensator which has sufficient capability and flexibility to manipulate a wide variety of payload geometries, yet without requiring continuous spring biasing.